James K Wetterer, Douglas B. Booher
Transactions of the American Entomological Society 149 (3), 315-324, (21 December 2023) https://doi.org/10.3157/061.149.0303
KEYWORDS: Basiceros genus-group, biological invasion, exotic species, native range
Eurhopalothrix floridana, a slow-moving, cryptic leaf-litter ant, is the only species in the Basiceros genus-group (formerly Tribe Basicerotini) found in the continental US. Before 2007, this species was reported solely from Florida. Researchers, however, questioned whether this species was native to Florida or if it was an exotic of undetermined geographic origin. Recent records of E. floridana from natural areas in Cuba (two sites), Dominican Republic (nine sites), and Isla de Mona, Puerto Rico (one site) suggest that E. floridana is probably native to the Greater Antilles. Here, we report new records of E. floridana from Florida and Georgia and consider evidence concerning whether this species is native or exotic to Florida. We compiled 121 earlier Florida site records of E. floridana, primarily in nature preserves, ranging from Key West (24.6°N) to Three Rivers State Park and Fort Clinch State Park (both 30.7°N). In 2012, we collected E. floridana at one site in Georgia: Crooked River State Park (30.8°N), the first record of this species in the state. In 2018–2022, we collected ants through leaf-litter extraction at 461 disturbed sites in Florida and southernmost Georgia (24.6°N–31.0°N), mostly under slash pine and oak trees growing by roadsides and parking lots. We found E. floridana in 69 of 229 leaf-litter extractions north of 28.5°N (including one record from Georgia: Saint Marys, 30.7°N), but in none of the 232 leaf-litter extractions south of 28.5°N. Co-occurrence analyses suggest that non-native ant species may be excluding E. floridana from disturbed sites in South Florida. The recent appearance of widespread E. floridana populations in north-central Florida is currently the strongest evidence that this species is not native to Florida. Genetic analyses are needed to evaluate more conclusively the status of E. floridana in Florida, Georgia, and the Greater Antilles.